1. Field of the Invention
The present invention relates to a data interleaving method and, more specifically, to a data interleaving method which raises the error correction capacity in a digital recording system. The method is particularly advantageous when employed in operating a system such as a digital video cassette recorder (DVCR). A corresponding apparatus is also disclosed.
2. Discussion of Related Art
In a DVCR system, the common method for promoting error correction capacity is called interleaving, whereby burst errors may be changed into random errors. In a DVCR system which does not perform data compression, i.e., a broadcasting DVCR system using D-2 or D-3 recording formats, the data correction capacity of the system is raised using a shuffling process. However, since a DVCR applying data compression cannot perform the shuffling process well, these DVCRs exhibit very poor protection against burst errors. Moreover, error propagation problems arise in systems applying data compression when the burst errors are of a magnitude exceeding the correction capacity of the respective decoder of the system, e.g., the DVCR.
FIG. 1 is a block diagram of a conventional data compressing and error correction encoding apparatus. A channel separator 11 separates and outputs input data in a plurality of channels. A data compressor 12 compresses the output digital data using a known data compression technique to produce compressed data and an outer encoder 13 adds outer vertical parities to each column of the compressed data. An interleaver 14 performs a "shuffling" function on the data to which the outer vertical parities were added in outer encoder 13, thus providing shuffled data. Inner horizontal parities are added to each row of the shuffled data by an inner encoder 15.
In a system to which data compression is not employed, data pixels are evenly scattered and recorded in various channels. Thus, even though data of a particular channel are damaged, the data of the damaged channel can be restored with data of the other channels using a "data concealment" technique. However, since a system to which data compression is applied has to consider the efficiency of data compression technique, such a system may not use the above-mentioned channel division method, and instead applies the so-called plane division method. It will be noted that when all the data for a particular channel becomes damaged in systems using the plane division error concealment technique, the applied technique may result in destroying all the data of the macro-blocks of a particular image.
A conventional sequential segment division method for one frame signal is illustrated in FIG. 2, wherein one frame signal, for example, consists of two fields of three segments each, i.e., six segments.
FIG. 3 shows a conventional data recording pattern for a tape recording data on a plurality of tracks. One frame signal is sequentially recorded on adjacent tracks on a tape, following the order of an assigned macro-block number and according to a field number, a channel number and a segment number, which are acquired by applying the segment division method depicted in FIG. 2. From FIG. 3 it will be noted that macro-blocks 0-324 for channels 1-4, which correspond to field 0 and segment 0, are recorded on tracks 1-4, macro-blocks 325-649 for channels 1-4, which correspond to field 0 and segment 1, are recorded on tracks 5-8, and macro-blocks 650-974 for channels 1-4, which correspond to field 0 and segment 2, are recorded on tracks 9-12. In the same way, the other macro-blocks are sequentially recorded in numerical order based on the segment number and the channel number in units of four tracks.
FIG. 4 shows a data format of an error correction code in an exemplary case where data is recorded on track 1. In FIG. 4, the macro-block data corresponding to field 0, channel 0 and segment 0, becomes damaged. FIG. 4 shows that macro-blocks MB0.about.MB324, denoted by hatch marks, include damaged data, wherein the data of the error correction code may include burst errors.
Therefore, as described above, if the segments are sequentially assigned according to macro-block number order, and macro-blocks which are included in the assigned segment are recorded on one track, it is nearly impossible to restore data when burst errors occur or when all of the data for a particular channel is damaged. In other words, the destruction of the data representing one whole track results in raising the burden for error correction accomplished by an inner decoding device. Accordingly, an error occurring in two whole tracks results in exceeding the error correction capacity of an outer decoding device.